Earthquake behavior of structures with copper energy dissipators

The earthquake behavior of structures with supplemental copper dampers is evaluated in this study. The investigation is divided into two parts: (i) an experimental work with seven pairs of hourglass copper dampers of different aspect ratios and side profiles; and (ii) a parametric study of 6-, 12-, and 25-story planar structures with elastic as well as inelastic behavior in the primary structure and copper dampers. The copper used in this study is electrolytic tough pitch (ETP) copper C11000; probably the most commonly used of all coppers; ductile, with a low-yield, and highly resistant to corrosion. Experimental results demonstrate that all copper plates reached stable angular distortions of the order of gamma - 25%, which implies transverse distortions in the devices larger than 40 mm. The behavior of the devices is highly dependent on the aspect ratio of the plate, h/t, and a recommendation is made to use plates in the range 11 less than or equal to h/t less than or equal to 18. Plates beyond this range exhibit either large stress and strain concentrations in the neck of the device or a strong influence of axial deformations in their cyclic behavior. The inelastic earthquake response of structures with such devices shows that drift reduction factors of the order of 30 to 40% can be achieved with reasonably economic designs. It is also shown that the efficiency of these devices depends on the soil conditions and flexibility of the primary structure. Finally, it is concluded that supplemental copper dampers are a good alternative for drift reduction in a wide ranLe of structural layouts, ranging from coupled shear-wall systems to moment-resi sting frames, and for impulsive as well as non-impulsive ground motions. Copyright (C) 2003 John Wiley Sons, Ltd.